ISI 03-1e Determination of Sulphated Ash in Starch at 525 oC

 ISI 03


ISI 03-1e Determination of Sulphated Ash in Starch at 525 oC

1. Scope The method is applicable to native, modified and hydrolysed starch.

 LT 12. Dec. 1966

Rev. LT 21. Nov. 1997

2. Principle Incineration of starch sample at 525 oC in the presence of sulphuric acid

3. Reagents

3.1 Sulphuric acid solution

Add 100 ml of concentrated sulphuric acid to 300 ml of distilled water.


Pour and mix carefully - use eye protection

3.2 Hydrochloric acid solution

Add 100 ml of concentrated hydrochloric acid to 500 ml distilled water


Pour and mix carefully - use eye protection

4. Apparatus

4.1 Analytical balance weighing to the nearest 0.1 mg.

4.2 Ashing dish of platinum or quarts

4.3 Electrically heated furnace.

4.4 Desiccator with dry drying agent

4.5 Bunsen burner

4.5 Water bath

 

5. Procedure Careful clean the ashing dish (4.2) and calcinate it 1/2 hour in furnace (4.3) at 525 oC.

Cool dish in desiccator (4.4) to room temperature and weigh on balance (4.1) to nearest 0.1 mg. Weight = w0 Clean always new dish in boiling HCl (3.2) and rinse in water

A sample of starch syrup may conveniently be dissolved in distilled water on a water bath (4.5) by 60 - 70 oC. The solution is allowed to cool to room temperature. An aliquot is used as test portion in stead of the sample itself.

Place 10 g of sample or an aliquot portion of a dissolved sample in ashing dish. Weigh on balance (4.1) to nearest 1 mg. Weight = w1 Take 2 g if ash >10% and 5 g if ash > 5%

Mix sample with 5 ml sulphuric acid solution (3.1). Rinse stirring rod with little water. Collect rinsing in ashing dish.

Incinerate the sample on a Bunsen burner (4.5) or equivalent until completely carbonised. Possibly pre-evaporate on hot plate or equivalent

Finish incineration in the furnace (4.3) at 525 oC until residual carbon has disappeared.

Cool. Moisten ash with several drops of sulphuric acid solution (3.1). Evaporate and incinerate again for 1/2 hour.

Incinerate 2 hours

Cool in desiccator to room temperature. Weigh immediately after removal from desiccator to nearest 0.1 mg. Weight=w2

 

6. Calculation Sulphated ash in percent of sample as is (average two results to the second decimal) =

Ash % = 100 x (w2 - w0) / (w1 - w0)

Correct eventually to dry basis

7 Notes Sulphuric acid facilitates ashing (wet combustion) and convert volatile chlorides into non-volatile sulphates.

Consider ash determination in hydrolysates by conductivity; ref: G. Tegge & G. Richter, Starch, 38 (1986) no. 4, 137-142)

 

8. Reference International standard: ISO 5809

Comments

Post a Comment

Popular posts from this blog

ISI 14-2e Determination of Acetyl Content

  ISI 14-2e Determination of Acetyl Content 1. Scope The method is applicable to acetylated starch   KM Rev. LT 14 Sep 1999 2. Principle Bound acetyl reacts with strong alkali and excess alkali is titrated   3. Apparatus 3.1 Burette 3.2 Conical flask, Erlenmeyer 250 ml with stopper   4. Reagents 4.1 Sodium hydroxide 0.1 N 4.2 Sodium hydroxide 0.45 N 4.3 Hydrochloric acid 0.2 N 4.4 Phenolphthalein: 1 g in 1 l ethanol 90%   5. Procedure Weigh 5 g of sample to the nearest mg. Transfer to conical flask (3.2) and disperse in 50 ml distilled water. Add a few drops of indicator (4.4) and titrate with (4.1) to permanent pink colour. Bound acetyl reaction Add 25.0 ml of NaOH 0.45 N (4.2). Stopper and shake vigorously for ½ hour Use mechanical shaker Titration  Flush stopper and neck of flask with a little distilled water and titrate excess alkali with 0.2N HCL to disappearance of pink colour. Blank 25.0 ml 0.45N NaOH (4.2) is titrated as a blank   6. Calculatio...
Read more

ISI 19-6e Determination of Viscosity of Starch by Brabender

Return 1. Scope The method is applicable to starch   LT 08.12.1966 Rev. LT 7. Feb. 2000. 2. Principle Viscosity of native and modified starch is measured during controlled heating and cooling   Dynamic viscosity 3. Apparatus 3.1 Brabender viscograph, 700 cmg cartridge. Bowl rotational speed: 75 rpm. Starting temperature: 45  o C. Subsequent rate of temperature increase and decrease: 1½  o C/min. Use standardisation kit for calibrating. Starting temperature = Start of test. 3.2 Beaker, 1000 ml 3.3 Laboratory scale   4. Procedure Weigh starch sample eq...
Read more

ISI 17-1e Determination of Viscosity of Starch by Brookfield

Image
ISI 17-1e Determination of Viscosity of Starch by Brookfield 1. Scope The method is applicable to native and modified starch - preferably starch for sizing of paper and textiles. LT 7. Oct. 2002. 2. Principle Viscosity of starch size prepared by indirect heating is measured as torque on a rotating spindle at constant speed and temperature 3. Apparatus 3.1 Brookfield Viscometer  RVDV-E (RV range) Alternative: LV range 3.2 Beaker, 1000 ml 3.3 Laboratory scale 3.4 Agitator with paddle stirrer IKA EUROSTAR digital + IKA paddle stirrer R1373 3.4 Boiling water bath and lid with slit for paddle stirrer Bath large enough for lid to cover bath and beaker 4. Procedure Weigh starch sample equivalent to 50 g (w) dry substance (DS) in a beaker (3.2) and add distilled water bringing total weight of starch and water to 500 g.  Put stirrer (3.4) in the beaker. Weigh the total weight of beaker, stirrer, starch and water (W g) Transfer beaker (3.2) to a boiling water bath. Attach stirrer to ag...
Read more